class ViewsBlock

class ViewsBlock extends ViewsBlockBase {
    
    /**
     * {@inheritdoc}
     */
    public function build() {
        $this->view->display_handler
            ->preBlockBuild($this);
        $args = [];
        foreach ($this->view->display_handler
            ->getHandlers('argument') as $argument_name => $argument) {
            // Initialize the argument value. Work around a limitation in
            // \Drupal\views\ViewExecutable::_buildArguments() that skips processing
            // later arguments if an argument with default action "ignore" and no
            // argument is provided.
            $args[$argument_name] = $argument->options['default_action'] == 'ignore' ? 'all' : NULL;
            if (!empty($this->context[$argument_name])) {
                if ($value = $this->context[$argument_name]
                    ->getContextValue()) {
                    // Context values are often entities, but views arguments expect to
                    // receive just the entity ID, convert it.
                    if ($value instanceof EntityInterface) {
                        $value = $value->id();
                    }
                    $args[$argument_name] = $value;
                }
            }
        }
        // We ask ViewExecutable::buildRenderable() to avoid creating a render cache
        // entry for the view output by passing FALSE, because we're going to cache
        // the whole block instead.
        if ($output = $this->view
            ->buildRenderable($this->displayID, array_values($args), FALSE)) {
            // Before returning the block output, convert it to a renderable array
            // with contextual links.
            $this->addContextualLinks($output);
            // Block module expects to get a final render array, without another
            // top-level #pre_render callback. So, here we make sure that Views'
            // #pre_render callback has already been applied.
            $output = View::preRenderViewElement($output);
            // Inject the overridden block title into the view.
            if (!empty($this->configuration['views_label'])) {
                $this->view
                    ->setTitle($this->configuration['views_label']);
            }
            // Override the block title to match the view title.
            if ($this->view
                ->getTitle()) {
                $output['#title'] = [
                    '#markup' => $this->view
                        ->getTitle(),
                    '#allowed_tags' => Xss::getHtmlTagList(),
                ];
            }
            // When view_build is empty, the actual render array output for this View
            // is going to be empty. In that case, return just #cache, so that the
            // render system knows the reasons (cache contexts & tags) why this Views
            // block is empty, and can cache it accordingly.
            if (empty($output['view_build'])) {
                $output = [
                    '#cache' => $output['#cache'],
                ];
            }
            return $output;
        }
        return [];
    }
    
    /**
     * {@inheritdoc}
     */
    public function getConfiguration() {
        $configuration = parent::getConfiguration();
        // Set the label to the static title configured in the view.
        if (!empty($configuration['views_label'])) {
            $configuration['label'] = $configuration['views_label'];
        }
        return $configuration;
    }
    
    /**
     * {@inheritdoc}
     */
    public function defaultConfiguration() {
        $settings = parent::defaultConfiguration();
        if ($this->displaySet) {
            $settings += $this->view->display_handler
                ->blockSettings($settings);
        }
        // Set custom cache settings.
        if (isset($this->pluginDefinition['cache'])) {
            $settings['cache'] = $this->pluginDefinition['cache'];
        }
        return $settings;
    }
    
    /**
     * {@inheritdoc}
     */
    public function blockForm($form, FormStateInterface $form_state) {
        if ($this->displaySet) {
            return $this->view->display_handler
                ->blockForm($this, $form, $form_state);
        }
        return [];
    }
    
    /**
     * {@inheritdoc}
     */
    public function blockValidate($form, FormStateInterface $form_state) {
        if ($this->displaySet) {
            $this->view->display_handler
                ->blockValidate($this, $form, $form_state);
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function blockSubmit($form, FormStateInterface $form_state) {
        parent::blockSubmit($form, $form_state);
        if ($this->displaySet) {
            $this->view->display_handler
                ->blockSubmit($this, $form, $form_state);
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function getMachineNameSuggestion() {
        $this->view
            ->setDisplay($this->displayID);
        return 'views_block__' . $this->view->storage
            ->id() . '_' . $this->view->current_display;
    }

}